Electric discharge apparatus



Jan. 7, 1941.

T. DRAPER 2,227,490

ELECTRIC DISCHARGE APPARATUS Filed April 14, 1958 53 87 51 sa 15' :Load 1 3 U 25 2 43 3 3 J 59 6? l WITNESSES: INVENTOR Tl'wmas Draper.

ATTORN Y Patented Jan. 7, 1941 UNITED STATES PATENT OFFICE ELECTRIC DISCHARGE APPARATUS Pennsylvania Application April 14, 1938, Serial No. 201,951

15 Claims.

My invention relates to control systems and it has particular relation to a system incorporating electric discharge apparatus responsive to low energy changes or impulses.

Control systems of this character made and operated according to teaching of the prior art, with which I am familiar, have certain degenerative characteristics which cause the system to be less sensitive than it could otherwise be. In general, a control system of this character comprises an electric discharge device controlled by a photosensitive device and energized from an individual unidirectional potential source of supply such as a rectifier. The electric discharge device in turn controls the operation of an electromagnetic device. The current passing through the discharge device for energizing the electromagnetic device depends upon a potential, controlled by the photoelectric device, impressed upon a first auxiliary electrode or control electrode of the discharge device. The impedance of the discharge device depends upon a potential impressed on a second auxiliary electrode or screen grid. As the current through the discharge device increases, the potential impressed upon the screen grid decreases, thus increasing the impedance of the discharge device. Therefore, for a certain condition of excitation less current is passed by the discharge device than would be passed had the potential impressed upon the screen grid remained substantially constant. Thus it was heretofore necessary to utilize a relatively large low energy change or impulse in the control electrode circuit to control the electric discharge device.

It is accordingly, an object of my invention to provide apparatus to increase the sensitivity of a control system incorporating an electric discharge device.

A more specific object or my invention is to provide apparatus for maintaining a potential impressed upon an auxiliary electrode of an electric discharge device substantially constant.

A further object of my invention is to provide apparatus responsive to the condition of excitation of an electric discharge device for maintaining a potential impressed upon an auxiliary electrode of the electric discharge device substantially constant.

Another specific object of my invention is to provide apparatus responsive to the condition of excitation of an electric discharge device for increasing the magnitude of a potential impressed upon an auxiliary electrode of the electric discharge device.

An incidental object of my invention is to provide apparatus for improving the voltage regulation of the source of supply.

According to my invention, I provide a control system comprising a first electric discharge device, having a plurality of principal electrodes and a. plurality of auxiliary electrodes, for controlling the operation of an electromagnetic device. The first electric discharge device and the electromagnetic device are energized, in response to a photoelectric device, from a source of unidirectional potential. To control the operation of the first electric discharge device, I also provide a voltage divider including a second electric discharge device having a plurality of principal electrodes and a control electrode. The control is such that when the current through the first electric device is varied, the potential impressed upon the control electrode of the second discharge device is varied thus adjusting the potential impressed upon one of the auxiliary electrodes of the first discharge device in a predetermined manner.

The novel features that I consider characteristic of my invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and its method of operation, together with additional objects and advantages thereof, will best be understood from the following description of a specific embodiment, when read in connection with the accompanying drawing in which the sole figure is a diagrammatic representation of a system of control organized in accordance with the present invention.

The apparatus shown in the drawing comprises an electromagnetic device ll having an operating coil l3 and a set of contacts l5, and an electric discharge device ll, preferably a high vacuum tube, having an anode 19, a cathode 2| and a plurality of auxiliary electrodes such as a control electrode 23, a screen grid 25 and a suppressor grid 21. The discharge device 11, and the operating coil l3, are supplied with electrical energy by means of a valve or rectifier 29 from a pair of energized conductors 3i and 33. The rectifier 29 comprises a plurality of anodes 35 and 31 and a plurality of cathodes 39 and 41. A capacitor 43 is connected between the cathode 39 and the conductor 33. A capacitor 45 is connected between the anode 31 and the conductor a control a circuit 85 of a load 81.

photoelectric device such as a photocell, having an anode 53 and a cathode 55. The photoelectric device 5| may be selectively connected to the circuit of the control electrode 53 by means of a multi-contact device 57.

A voltage divider 59 comprising a resistor ii and a second electric discharge device 63 is connected between the cathode 39 of the rectifier 29 and the conductor 33. The screen grid 25 is connected to a tap 65 on the resistor 6|. The discharge device 63, preferably a high vacuum device, comprises an anode Bl, a cathode 1| and a control electrode 69. The anode 61 is connected to the tap 65 of resistor 6| and the oathode H is connected to one end of the resistor 6|. A voltage divider 13 is connected between the anode |9 of the discharge device I! and the anode 37 of the rectifier 29. The control electrode 69 or" discharge device 63 is connected to a variable tap 5 on the voltage divider 13.

For the operation of the above described apparatus, it may be assumed that the multi-contact device 5'! is actuated so that anode 53 of the photoelectric device 5| is connected to a tap H on the resistor Si and the cathode 55 is connected to the control electrode 23 of the discharge device il. It is also assumed that a circuit interrupting device or switch 19 is closed. Thus when the photoelectric device 5| is dark, the discharge device [7 and therefore the operating coil I3 will be in the deenergized condition.

The resistor 6| will thus be energized through a circuit which extends from the energized conductor 3| through the switch 19, anode 35, cathode 39, resistor 6|, conductor 8|, to the energized conductor 33. The potentiometer 4'! will also be energized through a circuit which extends from the energized conductor 33, through conductor 8!, potentiometer 41, conductor 83, anode 3i and cathode 4| of rectifier 29, the switch 19 to the energized conductor 3|. Because of the difference in potential between the anode IQ of the discharge device I! and the conductor 83, the voltage divider 13 also becomes energized.

The variable tap i5 is so adjusted on the voltage divider 73 that the discharge device 63 is energized and a predetermined potential is impressed between the auxiliary electrode 25 and the cathode 2| of the discharge device I! when the discharge device l'i is deenergized. As the illumination upon the photoelectric device 5| increases the potential impressed between the control electrode 23 and the cathode 2| becomes more positive, and the discharge device I! becomes energized. Then as the control electrode becomes still more positive, the current through the discharge device |l increases. When the illumination on the photoelectric device 5| and thus the current through the electric discharge device ll reach a predetermined Value, the operating coil |3 becomes sufficiently energized to actuate the electromagnetic device H to close contacts IS. The contacts |5 may be utilized to The circuit for the operating coil |3 extends from the energized conductor 3| through the switch 19, anode 35 and cathode 39 of rectifier 29, operating coil I3, anode I9 and cathode 2| of discharge device i7, conductor 8| to the energized conductor 33.

As the current through the operating coil l3 increases the voltage drop through the coil in creases and the anode to cathode potential of discharge device |l decreases. Therefore, the

difference in potential across voltage divider 13 is decreased causing the control electrode 89 to become more negative with respect to the cathode The current through the discharge de vice B3 and therefore through the upper portion 89 of resistor 6| decreases. The resulting decrease in potential across the upper portion 89 of resistor 6i tends to cause the auxiliary electrode 25 to become more positive with respect to the cathode 2|. At substantially the same time, the increase in current through the operating coil l3 causes the potential between the cathode 39 and the conductor 8|, and therefore the potential across the voltage divider 59 to decrease thus tending to cause the auxiliary electrode 25 to become more negative. It will readily be understood that by properly selecting the constants of the circuit, the potential between the auxiliary electrode 25 and the oathode 2! may be maintained substantially constant, or increased, as the current through the operating coil l3 and the discharge device I1 is increased. Thus if the potential of auxiliary electrode is maintained substantially constant the impedance of the discharge device will remain substantially constant. Therefore less change in the potential between the control electrode 23 and the cathode 2| will be required to cause the discharge device to reach a predetermined condition of excitation.

It will also be noted that as the current through the operating coil |3 increases, the current through the voltage divider 59 is decreased, thus tending to maintain the current through the rectifier 29 more constant. This will improve the voltage regulation of the control system.

When the illumination upon the photoelectric device 5| is decreased, the control electrode potential of discharge device becomes more negative and thus the current through the operating coil |3 is decreased. The potential across the voltage divider 59 is increased causing the control electrode 53 to become more positive. The increased current through the discharge device 63 and thus the voltage divider 59 causes the potential between the auxiliary electrode 25 and the cathode 2| to be maintained at a predetermined value.

If the multi-contact device 51 is actuated so that the anode 53 of the photoelectric device 5| is connected to the control electrode 23 and the cathode 55 is connected to a tap 9| on potentiorneter 41, and the tap 49 is adjusted so that the control electrode 23 is properly energized, the discharge device I! will become conducting when the illumination on the photoelectric device 5| is below a predetermined minimum value. As the illumination is increased, the control electrode potential becomes more negative and thus the current through the operating coil I3 is decreased. The operation of the discharge device. 63 is similar to that hereinabove described, therefore, it is believed unnecessary to the understanding of the invention to repeat a description of these operations.

I do not wish to be r stricted to the specific structural details, arrangement of parts or circuit connections herein set forth, as various modifications thereof may be effected without departing from the spirit and scope of my invention. I desire, therefore, that only such limitations shall be imposed as are indicated in the appended claims.

I claim as my invention:

1. Translating apparatus comprising a first electric discharge device having a plurality of principal electrodes and a plurality of auxiliary electrodes, means for impressing a potential between the said principal electrodes, means for impressing a potential between a first of the said auxiliary electrodes, and one of the said principal electrodes, means for impressing a potential between a second of the auxiliary electrodes and one of the said principal electrodes and means including a second electric discharge device and means for impressing a potential across said second device depending on the conductivity of said first device for maintaining the said potential between the second auxiliary electrode and one of the principal electrodes of the said first device substantially constant.

2. Translating apparatus comprising a first electric discharge device having a plurality of principal electrodes and a plurality of auxiliary electrodes, means for impressing a unidirectional potential between the said principal electrodes, means for impressing a controlled potential between a first of the said auxiliary electrodes and one of the said principal electrodes, means for impressing a potential between a second of the auxiliary electrodes and one of the said principal electrodes and means including a second electric discharge device and means for impressing a potential on said second device depending on the conductivity of said first device for maintaining the said potential between the second auxiliary electrode and one of the principal electrodes of the said first device substantially constant.

3. Translating apparatus comprising a first electric discharge device having a plurality of principal electrodes, a control electrode and a plurality of auxiliary electrodes, means for impressing a unidirectional potential between the said principal electrodes, means for impressing a variable potential between the said control electrode and one of the said principal electrodes, means including a voltage divider for impressing a potential between one of the said auxiliary electrode and one of the said principal electrodes, and means, including a second electric discharge device associated with the said voltage divider and having a potential impressed thereon which depends on the conductivity of said first device for maintaining the said potential between the said auxiliary electrode and one of the said prinvice associated with the said voltage divider for maintaining the said potential between the said auxiliary electrode and one of the said principal electrodes of the said first device substantially constant, and means cooperatively associated with the said first device for controlling the said second device.

5. Apparatus for controlling the supply of power from a power source to a power-consumption system comprising an electric discharge device, having a plurality of auxiliary electrodes and a plurality of principal electrodes, means for energizing the said device including means for impressing a potential between a first of the said auxiliary electrodes and one of the said principal electrodes, means associated with a second of the said auxiliary electrodes for varying the excitation of the said device, means controlled by the said device, when its excitation is varied, for controlling the supply of power from a power source to a power-consumption system, and means responsive to the conductivity of said device' for maintaining the potential between the said first auxiliary electrode and one of the said principal electrodes substantially constant.

6. Apparatus for controlling the supply of power from a power source to a power-consumption system comprising an electric discharge device, having a plurality of principal electrodes and a plurality of auxiliary electrodes, means for normally maintaining the said device in a predetermined condition of excitation, means associated with a first of the said auxiliary electrodes for varying the excitation of the said device, means for impressing a potential between a second of the said auxiliary electrodes and one of the said principal electrodes, means controlled by the said device, when its excitation is varied, for controlling the supply of power from a power source to a power-consumption system, and means cooperatively associated with the said device for increasing the potential between the said second auxiliary electrode and one of the said principal electrodes when the current increases through the said device and the means for controlling the supply of power.

7. Apparatus for controlling the supply of power from a power source to a power-consumption system comprising a first electric discharge device, having a plurality of principal electrodes and a plurality of auxiliary electrodes, means for normally maintaining the said first device in predetermined condition of excitation, means associated with a first of the said auxiliary electrodes for varying the excitation of the said first device, means for impressing a potential between a second of the said auxiliary electrodes and one of the said principal electrodes of the first device, means controlled by the said first device, when its excitation is varied for controlling the supply of power from a power source to a power-consumption system, and means, including a second electric discharge device, responsive to the conductivity of said first device and said means controlled by the said first device for maintaining the potential between the said second auxiliary electrode and one of the said principal electrodes of the said first device substantially constant.

8. In a control system comprising an electric discharge device having a plurality of principal electrodes and a plurality of auxiliary electrodes, means for normally maintaining the said device in a predetermined condition of excitation, means associated with a first of the said auxiliary elec trodes for varying the excitation of the said device, means for impressing a potential between a second of the said auxiliary electrodes and one of the said principal electrodes, means controlled by the said device when its excitation is varied and means cooperatively associated with the said device for increasing the potential between the said second auxiliary electrode and one of the said principal electrodes when the current through the means controlled by said device increases.

9. In a control system, in combination, electromagnetic means, a source of power for the said electromagnetic means, an electric discharge device for controlling the supply of power from the power source to the said electromagnetic means, the said discharge device having a plurality of principal electrodes and a plurality of auxiliary electrodes, means for normally maintaining the said discharge device in a predetermined condition of excitation, means associated with a first of the said auxiliary electrodes for varying the excitation of the said discharge device means for impressing a potential between a second of the said auxiliary electrodes and one of the said principal electrodes, and means cooperatively associated with the said discharge device for increasing the potential between the said second auxiliary electrode and one of the said principal electrodes as the current between the principal electrodes increases.

10. In a control system, in combination, an electromagnetic device, means including a first electric discharge device for connecting the said electromagnetic device to a source of power, the said first discharge device having a plurality of principal electrodes and a plurality of auxiliary electrodes, means for normally maintaining the said first discharge device in a predetermined condition of excitation, means associated with a first of the said auxiliary electrodes for varying the excitation of the said first discharge device, means for impressing a potential between a second of the said auxiliary electrodes and one of the said principal electrodes of the first discharge device, and means, including a second electric discharge device, responsive to the conductivity of said first discharge device and said electromagnetic device for maintaining the potential between the said second auxiliary electrode and one of the said principal electrodes of the said first discharge device substantially constant.

11. In combination, a power supply source, a main electric discharge device having a plurality of principal electrodes and a plurality of auxiliary electrodes, impedance means in series with the said electric discharge device, a first potentiometer connected across said source, said first potentiometer having an intermediate tap connected to one of the auxiliary electrodes of said main discharge device, an auxiliary electric discharge device shunted from said one auxiliary electrode to one of the principal electrodes of said main discharge device, said auxiliary discharge device having a control electrode, and a second potentiometer connected to draw current from said source, said second potentiometer having an intermediate tap connected to said control electrode of the second auxiliary discharge device.

12. In combination, a power supply source, a main electric discharge device having a plurality of principal electrodes and a plurality of auxiliary electrodes, impedance means in series with the said electric discharge device, a first potentiometer connected across said source, said first potentiometer having an intermediate tap connected to one of the auxiliary electrodes of said main discharge device, an auxiliary electric discharge device shunted from said one auxiliary electrode to one of the principal electrodes of said main discharge device, said auxiliary discharge device having a control electrode, and a second potentiometer connected to said source so that a portion of said impedance means intervenes between the point of connection of said second potentiometer and the point of connection of said first potentiometer, said second potentiometer having an intermediate tap connected to said control electrode of the second auxiliary discharge device.

13. In combination, a power supply source, a main electric discharge device having a plurality of principal electrodes and a plurality of auxiliary electrodes, impedance means in series with the said electric discharge device, a first potentiometer connected across said source, said first potentiometer having an intermediate tap connected to one of the auxiliary electrodes of said main discharge device, an auxiliary electric discharge device shunted from said one auxiliary electrode to one of the principal electrodes of said main discharge device, said auxiliary discharge device having a control electrode, a second potentiometer connected to said power supply source, and a second power source connected to said second potentiometer in series with said power supply source, said second potentiometer having an intermediate tap connected to said control electrode of the second auxiliary discharge device.

14. Apparatus for controlling the supply of n a potential between a second of the said auxiliary electrodes and one of the said principal electrodes, a second auxiliary discharge device shunted between the second auxiliary electrode and said one principal electrode, said second discharge device having a control electrode, and means to control said control electrode in response to variations of current through said first discharge device.

15. Apparatus for controlling the supply of power from a power source to a power-consumption system comprising a first electric discharge device, having a plurality of principal electrodes and a plurality of auxiliary electrodes, means for normally maintaining the said first device in a predetermined condition of excitation, means connected to a first or" the said auxiliary electrodes for varying the excitation of a first of said auxiliary electrodes, means for impressing a potential between a second of the said auxiliary electrodes and one of the said principal electrodes a second auxiliary discharge device shunted between said second auxiliary electrode and said one principal electrode, said second discharge de vice having a control electrode, and means to render said control electrodes less positive as current through said first discharge device increases.

THOMAS DRAPER. 

